More GPs should be trained to deal with long-term conditions to prevent the NHS being "overwhelmed" by the fast-growing number of patients with multiple health problems, a senior NHS figure said.

Martin McShane, NHS England's national director for people with long-term conditions, said the issue was "the healthcare equivalent to climate change" and required urgent attention.

He told The Guardian that there was too big a gap between specialist care and that available from family doctors, suggesting practices should join forces to provide "complex care" GPs dedicated to the issue.

Over the next four years, the number of patients with three or more long-term conditions is expected to rise from 1.9 million to 2.9 million due to the ageing population and changing lifestyles.

With 70% of the £110 billion NHS budget spent on the 15.4 million with at least one - and £10.9 million of the £15.5 million social care spend - something had to be done, Dr McShane told the newspaper.

"I would say it's the healthcare equivalent to climate change," he said.

"It is putting pressure into the system, which, unless we change the way we address the problems, will overwhelm the system.

"This is the biggest problem facing the health system and the care system and the costs are growing year on year. They are huge already and they will continue to grow."

Those with multiple conditions " often fall through the gaps" between specialist treatment and GP care, leading to avoidable spells in hospital that drain resources and increase pressure on A&E wards.

Dr McShane said: "General practice is doing a fantastic job, as it always has done, and specialists have become more and more specialised. But there's the needs of a new generation, the geriboomers, who are now living longer and collecting long-term conditions, so our thinking has to change."

As many as 50 practices could join forces to create small teams to enable patients to be treated at home, he suggested.

Care and Support Minister Norman Lamb said: "We want to build a fairer society, and that means providing better care to people with long-term conditions so that they are able to enjoy an independent, fulfilling life, and have the support needed to manage their health.

"We are investing £3.8 billion to join up health and social care services so that people can live as independently as possible for as long as possible.

"Fourteen areas of the country have been identified as Pioneers in joined up, integrated care. They are leading the way in demonstrating how to improve care for those with long-term conditions.

"We have also made changes to the GP contract to bring back the personal link with patients so GPs can focus on giving people the care they need and preventing unnecessary trips to hospital.

"NHS England is already taking action to make sure patients are at the heart of decisions about their care and doctors and nurses have the right tools to drive improvements in care for people with long-term conditions now and in the future."